The use of medicament inhalers for the treatment of diseases or disorders is well known. Such inhalers are generally referred to as Metered Dose Inhalers (MDI).
A common type of MDI is what is known as a pressurised Metered Dose Inhaler (pMDI). Such inhalers generally comprise a medicament canister and an actuator. The medicament canister contains medicament under pressure and is designed to deliver a metered dose of medicament in the form of an aerosol spray. The actuator generally comprises a substantially L-shaped hollow tube which has a first open end adapted to receive the medicament canister, and a second open end which acts as a mouth piece.
Medicament canisters for use with a pMDI generally have a spray stem extending from one end which is adapted to engage with a spray-directing element housed within the actuator, and adjacent to the mouth piece of the actuator. When the canister is pushed down into the actuator, the spray stem and spray-directing element combine to direct a metered dose of medicament out through the mouthpiece and into the mouth of the user.
Another common type of MDI is what is known as a Dry Powder Inhaler (DPI). DPI's are generally in the form of a disc or grinder which may be rotated, or otherwise actuated, in order to dispense a metered dose of dry powder into an appropriate receptacle such as a mouthpiece. The dry powder may then be inhaled by the user, for example, by sucking strongly through the mouthpiece.
Further examples of medicament inhalers include delivery devices such as nebulisers and nasal sprays. Such delivery devices are generally designed to supply a dose of medicament in the form of a fine mist, which is directed either into the mouth or nasal cavity of a user.
Some medicament inhalers are kept on hand for use in a specific event or emergency. For example, if a person were to have a sudden asthma attack, they may reach for a medicament inhaler which contains what is generally known as a “reliever” medicament. A reliever medicament is fast acting and in most cases will relieve (or reduce the severity of) an asthma attack, almost instantaneously.
Other medicament inhalers are designed for regular use in order to prevent an event such as an asthma attack and/or to manage or control a disease such as asthma. Such inhalers are generally known as “preventers” because the regular use of such inhalers serves to prevent (or minimise the likelihood of) an asthma attack. The regular use of preventer medicament by asthma sufferers is generally effective in controlling the disease and/or preventing the vast majority of asthma attacks. Commonly, preventer medicament for asthma sufferers is taken twice a day, usually at a set time in the morning and in the evening.
There are now also available “combination” medicament inhalers which combine both a reliever and preventer medicament.
Studies have shown that many people overuse their reliever medicament, for example by using it when only mildly short of breath. The overuse of a reliever medicament has the potential to reduce the effectiveness of the medicament, which may render the medicament less effective in times of real need, for example during a severe asthma attack.
Moreover, a patient's increased use of a reliever medicament over a period of time may be indicative of a pending exacerbation event.
It would therefore be of advantage if there was available a device for monitoring patient usage of a reliever medicament inhaler in order to determine any potential overuse and/or for predicting a potential exacerbation event, prior to the event occurring.
A problem or difficulty associated with the use of preventer (or “combination”) medicament inhalers is poor medicament compliance. That is, many studies have shown that users frequently do not take their medicament at the predetermined or prescribed times and/or in the required amounts.
The consequences of poor medicament compliance are reduced disease control, lower quality of life, lost productivity, hospitalization and avoidable deaths.
Not only is compliance to preventative medicaments typically low, but it has also been shown that actual compliance by a user is lower than the same user's estimated compliance.
In order to address these problems and difficulties, there are available a number of compliance monitoring devices for use with medicament inhalers.
Virtually all compliance monitoring devices incorporate dose counting means. In a general sense, dose counting means provide the simplest embodiment of a compliance monitor, as the dose count may indicate the number of medicament doses delivered and/or the number of medicament doses remaining in the medicament inhaler (the latter known as an “absolute dose counter”). The doses dispensed or remaining may also be displayed on a dosage counter, such as an LCD display, housed on the medicament inhaler.
The earliest dose counting mechanisms for pMDI's usually incorporated mechanical dose counting switch mechanisms such as levers or springs or trigger rods—which were mechanically actuated by movement of the canister within the actuator when a dose of medicament was dispensed. For example, see U.S. Pat. No. 4,817,822 (Rand et al) and U.S. Pat. No. 5,020,527 (Dessertine).
There are several problems associated with the use of such mechanical dose counting means. Firstly, the mechanical switch mechanisms include moving parts which may suffer wear and tear or otherwise deteriorate over time. Secondly, the switch mechanisms could break off and enter the medicament delivery pathway, and be inadvertently swallowed by the user. Thirdly, the mechanical switch mechanisms, which are commonly housed inside the actuator, can change the airflow characteristics of the inhaler, which may adversely impact on the medicament delivery performance of the inhaler. Lastly, mechanical switch mechanisms may be inadvertently triggered by the user, for example during washing of the actuator body to clean away any built up medicament residue (which must be done from time to time).
In recognition of some of the above problems or difficulties, U.S. Pat. No. 6,601,582 (Rand et al—but referred to herein as “GSK”) describes a mechanical dose counter which is integrally formed on the medicament canister. However, a disadvantage associated with GSK is that the incorporation of a dose counting mechanism into each and every medicament canister adds cost to the end user. Moreover, given that each canister typically contains a one month supply of medicament, it is economically and environmentally wasteful to supply and then discard such technology with each month's medication.
More recent dose counting mechanisms incorporate electronic counting means. For example, see U.S. Pat. No. 5,544,647 (Jewettt et al). U.S. Pat. No. 6,202,642 (McKinnon et al) and US Patent Publication No. 2005/0028815 (Deaton et al).
However, most electronic dose counting mechanisms also rely on the canister physically engaging with a switch mechanism for the purpose of closing an electrical switch (to indicate a dosage count of one). For example, in order to record a dosage count of one. Jewett includes a microswitch (42) which is physically engaged by the leading edge (19) of a sleeve (17) which is attached to the canister (16)—see FIG. 1. Similarly, Deaton utilises a ramp portion (42) which is physically engaged by the shoulder (26) of the canister (14) during the dispensing of a dose of medicament—see FIGS. 22a and 22b. 
Hence, because such electronic dose counting means also include moving parts, these parts are likewise susceptible to wear and tear and/or deterioration over time (they may also be susceptible to breaking off and/or interfering with the airflow within the inhaler).
Furthermore, the fitting of mechanical or electronic dose counters to an inhaler usually requires modifications to the inhaler, for example the drilling of a hole in the side of the actuator or the attachment of a cap or sleeve to the canister. The fitting of such dose counters to an inhaler can therefore be a fiddly or time consuming operation.
More importantly however, any modifications made to the actuator (or canister) have the potential to interfere with the airflow characteristics within the actuator, possibly affecting the effectiveness of delivery of a dose of medicament. This may result in the patient not receiving the required amount of medicament in order to treat the disease.
Any modifications made to the actuator may also be prone to disruption when washing the actuator. This may subsequently result in inaccurate dose counting or compliance monitoring (Jewett and Deaton address this issue by housing the compliance monitoring means within a hermetically sealed housing—which increases cost and manufacturing complexity).
Most mechanical or electronic dose counters are designed to be absolute dose counters. That is, when a new medicament canister is placed in the actuator, the counters are either manually or automatically set to the number of doses remaining in the full canister (typically around 120 doses which usually comprises one month's supply of a preventer medicament). The GSK device referred to previously is an example of an absolute dose counter (but formed on the canister, rather than the actuator).
Every time a dose of medicament is dispensed, the dose counter serves to reduce the displayed number of doses remaining by one. Hence a user is able to keep track of the number of doses remaining in the canister, and can therefore ensure he/she has a replacement canister at hand prior to when the first canister is due to run out.
A disadvantage associated with absolute dose counters is that they are dedicated to only one canister at a time. Hence, they are not able to monitor the ongoing compliance characteristics of a user over a period of time which may involve the user going through many canisters of medicament. Moreover, absolute dose counters are not able to monitor a person's usage over all four seasons to determine useful information such as any seasonal fluctuations. Absolute dose counters are also not able to monitor the ongoing compliance characteristics of a user should they change medications when only half way through an existing canister.
Presently available electronic compliance monitoring devices also include means to record a range of compliance data, in addition to dose counting. For example. Dessertine includes a timer to indicate time between doses. McKinnon includes an electronic module to record date and time as well as more comprehensive patient usage information.
Most electronic compliance monitoring devices are integrally formed with the inhaler, usually by being mounted on, or integrally formed with, the actuator body (eg, see Jewett and Deaton). This presents its own difficulties or limitations.
Firstly, because the compliance monitoring device is integrated with the medicament inhaler, it cannot generally be reused for longer than the life of the inhaler. Furthermore, compliance monitoring technology, and especially electronic compliance monitoring technology, adds cost when integrated into each and every inhaler.
However, reusing an actuator over more than one medicament canister can lead to residual medicament build-up that reduces the quantity of the drug delivered by the inhaler, and can also change the deposition properties of the aerosol particles, meaning patients get less medication.
Furthermore, repeatedly discarding the plastic and electronic compliance monitoring technology also creates an environmental sustainability problem that needs to be addressed. Additionally, as not all disease sufferers exhibit poor disease control or poor compliance, it is wasteful to provide such features embedded into each inhaler of a given type.
Perhaps partly in recognition of the above disadvantages associated with inhalers with integrally formed compliance monitoring means, McKinnon describes an electronic module which is releasably attachable to a sleeve which is fitted to the actuator. However, the removal of the electronic module from the sleeve renders the sleeve inoperable, which must then be removed and discarded, which is wasteful and expensive. Furthermore, the electronic module must be reprogrammed once it has been removed from the sleeve and prior to the module being fitted to another sleeve. Moreover, the fitting of the sleeve and electronic module to an inhaler is a time consuming and complex operation—which may present significant operational difficulties, especially for young children, the elderly or people of reduced mental capacity. Furthermore, the sleeve is preferably designed for attachment to only one specific brand of actuator. Hence, the McKinnon device cannot be used across a range of different actuators.
U.S. Pat. No. 5,564,414 (Walker et al) describes the concept of a removable sleeve designed to fit the body of a manufacturer's inhaler. However, Walker uses a mechanical counting mechanism (an external plunger-type trigger rod), which has the same disadvantages generally associated with mechanical counting means, as referred to previously.
PCT/US 2008/052869 (Levy et al) describes a sleeve housing which is releasably attachable to an actuator body. The sleeve housing includes electronic monitoring apparatus and the device is designed to monitor usage in order to predict an exacerbation event. However. Levy relies on a counting means which requires attachment of a cap to the canister which is adapted to engage with a dose-dispensing sensor during the delivery of a dose of medicament. Hence, Levy requires modifications to the inhaler prior to being able to be used—which has the potential, over time, to interfere with the effectiveness of the inhaler to properly deliver medicament.
Levy also discloses the use of wireless technology to transmit compliance data to a remote device such as the laptop of a health professional. This data may be transmitted in real time or at predetermined set times.
Furthermore, the sleeve components described in McKinnon. Walker and Levy would not be able to be used in relation to a medicament canister already fitted with an absolute dose counter, eg the GSK device referred to previously.
Another problem associated with integrated electronic compliance monitoring devices is that many drugs are regulated and require exact actuator conformity. That is, there should be no modifications made to the actuator structure as any modifications may distort the reliability of the delivery of the medicament. Moreover, physicians, researchers, insurance companies, and so on, would not want to risk (for example, in terms of liability) the possibly of affecting the proper delivery of the medicament through these dedicated electronic instruments without the same assurance of proper drug delivery as with the commercial actuator provided by the drug manufacturer.
Having regard to the foregoing, it would therefore be of advantage if there was available a device for monitoring patient usage of a medicament inhaler which was releasably attachable to range of different medicament inhalers, and without any modifications being required to the inhaler.